Oil Painting Over an Acrylic or Watercolor Underpainting – Which is Best?

Oil painting over acrylic or watercolor underpaintings is a technique you can use for Plein Air or studio painting. But which one is best for oil painting – acrylic or watercolor? In this video, I discuss that question.

The idea of using acrylic paints to create the initial underpainting washes came up recently during one of our members’ Online Workshops and Q&A sessions. Many professional artists will begin with an acrylic underpainting, let it dry, and then use oil paint on top of the acrylics. Are there any downsides to that technique?

In this video I discuss why using watercolors might be better than acrylics for the initial washes of an oil painting. I also share what I’ve learned from the most recent art materials research about using acrylic gesso or grounds for oil painting. Why does oil paint stick to acrylic paint but acrylic doesn’t stick to oil paint?

At the end of this post, you will find the complete written transcript from the video in case you would rather read than listen.

When I talked with some other professional artists who are using acrylic paints for their initial washes, I decided I would try it out myself. It sounded convenient and I thought it might speed up my painting process. But I never quite got around to actually trying it out.

Now that I know about using watercolors for the initial underpainting I will definitely do some experiments with that technique. I love the possibilities of trying out different design ideas quickly and easily.

Here’s the video transcript:

Oil Painting Over Acrylics or Watercolors – Which is Best.mp4

[00:00:00] So I’ve had a lot of our members that have asked about using acrylics to do the washes, the initial washes on a painting and then painting oils over that. Is that a good idea or not? I’m going to talk about that right now.

[00:00:26] All right, so the science behind all of this is pretty tricky. I had to go through a lot of different research papers and everything else to get a good handle on the best practices when it comes to painting oils over acrylics.

[00:00:46] So I use, I’ve been using acrylic grounds since the 90s. In the 80s and the early 90s my dad and I, we actually made, we did it all from scratch. We painted on linen. In fact, this canvas right here, this is one of the canvases we did back in about ’88, ’89. So pretty old. And you can see, I mean this thing is still tight as a drum. Beautiful stuff. And it was done with a lead primer. And I have a big roll of lead primed linen in my back tool room which I’ve had for about 10 years. I haven’t used it for a long time.

[00:01:37] In producing this kind of thing, this lead primed canvas, it’s pretty toxic stuff. And the process for that is generally you have to protect the canvas from the oil, because oil will, at least on natural fibers like canvas, it will rot it – it will deteriorate it. And over time, that’s really bad for the paintings as well. Especially if you don’t have anything that’s holding it together, that’s not gonna work out too well. And part of the thing with all that is all the things we have to use to get to that point, like Turpentine and Solvents, and other solvents – things that are just terrible for our health.

[00:02:24] And then I started to read some papers by some conservators back in the 90s. And there really wasn’t – there still isn’t – there are a lot of unknowns out there. And the National Gallery of Art, the Tate Museum, all these different museums around the world, different researchers, are trying to figure out the best way to restore and prevent, restore old paintings and prevent paintings today from deteriorating worse than they have, or ones that haven’t really deteriorated that much, how do we keep paintings today from getting into any bad condition like cracking, and de-laminating – there’s all kinds of different things that can happen with the painting. So with something like lead primed linen, you had to use a size that usually ends up being like an animal skin glue, rabbit skin glue, because it will protect the surface of the canvas, the natural fibers, from the oils that go on top, especially the primer that we put on there, it protects it from that and keeps it from rotting. The problem with animal skin glues is that they’re hygroscopic. They absorb moisture from the air. And if there’s enough moisture – if the humidity gets to be – I don’t know, if we lived somewhere like the Amazon and the humidity is just crazy high, it’ll absorb that moisture and that can cause problems because it never actually dries. OK, it does dry, but if it gets wet again, it will go back into its wet consistency. So the more water that it absorbs, the more problems it can create. And that’s not good for our oil paintings. Besides that, even with an oil primer like this, I’ve had this for quite a while, this Gamblin oil ground, oil painting ground, these things are toxic to breathe, the fumes from them are terrible.

[00:04:34] So on wood, you could use something like that and it would be just fine. If you have it on a wood panel, the wood’s not going to deteriorate because of painting oil on it. The problem with wood, we don’t want to just paint oil straight on wood because the wood is so absorbent, it’s going to take all the oil binder out of the oil paints and then they become flaky. And we don’t want just pigment. If we could just use pigment, we would do that. It has to have something to bind it together to keep it stable so it’s not in powder form. Otherwise, we could just brush it off of there or blow it off of there, right? So with wood, if we just painted oil right on wood, it absorbs so much of that oil binder that it becomes unstable – the oil paint does. So we use something like a a ground like an oil ground or a lead ground or an acrylic ground.

[00:05:27] So in the 90s, I read this conservator that said that testing at that time was showing that acrylic grounds, oil paints over acrylic grounds, were actually working out better in the long run than the traditional using hide skin or animal skins and glues and stuff like that. So I thought I’m good. I’ll jump ship right now because I didn’t like the toxic fumes from an oil ground. I didn’t like the incredible preparation that went into a led ground and then having to wait six months to a year to be able to use that to paint on. That’s a crazy amount of time invested there.

[00:06:05] So all of those things – I want to be able to put together my canvas, my panel, whatever it is, and paint quickly. I’m not much for the busy work kind of thing, especially cleaning brushes and stuff like that. But I also am very adamant about staying healthy because my final, one of my main art professors that I’d go out painting with, that I learned my more Russian bravura style of painting from, by the time he was 65, he couldn’t paint with oils anymore. He’d use turpentine and things like that so much in his studio without good ventilation that it had, he had built up this toxicity in his body. He just got around it and he got sick. So I decided early on that was a good example for me. Bad for him. Good example for me of keeping myself healthy.

[00:06:59] So I jumped ship quick when I read that a conservator was saying to do that. But then, of course, we keep, things go back and forth and there a lot of people are saying like Gamblin today, Robert Gamblin, he deters oil painting artists away from using an acrylic ground because it’s only been around since the 50s, and he says that with the traditional it’s been around for hundreds of years. That’s true. But with the tests that they’ve done with oil paints over an acrylic ground, there have been no problems except from something like zinc oxides. That’s a completely different problem that they’re talking about there. But as far as the adhesion goes, oil paints adhere really well to acrylics.

[00:07:48] And yet when it comes to using acrylic paints for our initial washes, I’m going to say no. And let me tell you why. So this is what I’m using nowadays. Either, you know, they come in black or white. This is ABS plastic. I use ABS plastic panels to paint on because I found out that the MDF panels that I was using forever have formaldehyde in them, which leaches out into my studio, into the air here, and I’m breathing that all the time. I still have a ton of MDF panels around, but unless they’re sealed really well with something like an Ecos air-purifying primer, it’s one of the only things I’ve found that you can paint all the sides and everything front back and all the sides of the panel with that Ecos air-purifying primer, and it will actually seal in formaldehyde and all the other VOC’s that are escaping into the air. That’s a real hassle as well. And it’s highly absorbent. The problem with a highly absorbing ground for oil paints is that if it’s too absorbent, it’s going to be like that wood. It’s going to pull the oils out of the oil paint. And the oil is the binder. It’s what keeps it, it’s what forms that strong shell on the oil paints. So we don’t want that. We don’t want to get too absorbent.

[00:09:14] A regular acrylic Gesso is absorbent, but it’s not so much that it’s going to pull too much of the oil out of there. If we’re worried about it, we can always put just a layer of oil on our painting before we even start. Watch that, though, because if you get too much oil. Let me explain this here. If you get too much, oil is going to bead up on there. Why does it bead up? Because…the reason why oil adheres to acrylic and not the other way around – Acrylic will not adhere to oil paints if you paint acrylic on top of it. Yes, some people have done that and they say “my paints are still there a few years later”. The problem is if they go over and they flex that at all or they take like a palette knife and they start to peel it, it will peel right off of there because there is no kind of a bond there. With oil to oil, it’s a chemical bond. With acrylic to acrylic, It’s a chemical bond. They start to fuse to one another – the oil to oil and acrylic to acrylic.

[00:10:16] With oil on top of acrylic, why does it work? Because acrylic even in a state like this where it’s hard – see this stuff, doesn’t flex at all hardly. This is a quarter-inch ABS panel. And I love this stuff. It’s great. It’s nice and stable, although it depends on the brand, too. I get these from a local plastics company and you can see that if I take this one, it’s a quarter inch. I can still flex it, but I had to put quite a bit of pressure on it. Now, if I get it to a panel like the size of, whoa, where’s it at?  Right back there. I have a 30×40 inch panel that I’m getting ready to paint on. You start getting into big sizes like that, even the quarter-inch gets a lot more flex in it. That can be dangerous for oil paints. Once they’ve dried. But in the initial stages, oil paints are very flexible for years down the line. They continue to be just as flexible as, or I can’t say just as flexible, but they have extreme flexibility to them for at least two to three years down the line.

[00:11:23] So I’m not worried about that with my acrylic panels for a while because I’m going to be putting the painting into a frame. That frame is going to keep them from flexing. It’s still a lot more stable than trying to do it with a canvas, like this linen canvas behind me, or a cotton canvas. Those things have a lot more flex to them. I used those things for a long time, almost 20 years before I switched to MDF panels and then I switched just recently to ABS plastic.

[00:11:50] Now getting back to ABS plastic, or to any kind of acrylic or plastic? Why does oil paint adhere to it? Because it’s full of little tiny microscopic holes. Those holes allow the oil to go in and grab into it. And that’s where that mechanical bond comes from. It’s those little tiny, porous holes in the acrylic. No matter how, even on a glossy surface, they’ve done tests with glossy, more glossy surfaces with acrylic, and the oil paint still adheres to it. It still bonds with it. They do all kinds of crazy tests with folding it and all that sort of thing like on a canvas. It still holds to it because it’s getting into those little porous holes. Every bit of plastic is porous. It’s just porous. And so that’s where the oil is getting in there and binding to it.

[00:12:48] Now, I wouldn’t suggest yet, I’m going to do some tests with it, I wouldn’t suggest yet using it with this really highly glossy surface that it comes with. This is how ABS plastic comes – this first glossy surface and then a, like a pebbly surface on the back, a textured surface. But both of them are pretty slick. So I take a 60 grit sandpaper and I sand all that gloss off of it and then no problems at all. I have tested this where I go in and I try to scrape it off. It will not scrape off of there after just a month or two of drying. I’ll go in and try to scrape it off with my palette knife, with a razor blade, with all kinds of stuff. It is bonded to that stuff. It’s not coming off of there. And that’s because of that porosity.

[00:13:37] So why not use acrylic paints then, which also have porosity to them? Why not use that for our initial washes? Because they dry faster and it’s stable enough to paint oil paint over the top of it. The reason for that is because most of us, in fact, I didn’t realize this until recently, even though acrylic paints will dry to the touch in about 30 minutes, it’s not actually dry all the way through, even with thin layers for two to three days. And we’re not supposed to paint on top of acrylic with oil until it is thoroughly dry. It’s kind of like what they say about varnishing any kind of painting. Wait until it’s thoroughly dry.

[00:14:21] Although now with the, this is the varnish I use now, the Gamvar. I think Golden has a good one, too. This stuff can be removed with mineral spirits. Excellent, excellent varnish. It doesn’t yellow. It always stays that clear color. And you can take it off with mineral spirits, which is the most mild solvent that we have (at least for oil painting). So this varnish, Gamblin developed this in connection with the National Gallery of Art. They worked together on it. That’s what they came up with. And Golden has something, I think comparable to it. I don’t know a lot about Golden’s varnish, but you can varnish that over oil, acrylic, Alkyd, anything like that. So it works for both oil and acrylic, which is really nice.

[00:15:11] The thing about oil paints, first of all, when people are out on location, especially for Plein Air painting, we’re wanting to paint quickly, we have a short period of time. That’s why some people – I paint wet into wet, so it’s not a big deal for me to do my early washes in oil – I just paint right back into them. That doesn’t concern me. Some people love the idea of having that initial wash dry when they go to paint back on top of it. And since acrylic dries so quickly, they can do that in a relatively short period of time. The problem is now we know that it takes two to three days for acrylics to dry. Nobody when they’re Plein Air painting, wants to wait two to three days for that initial wash to dry before they paint on it.

[00:15:56] Another thing is, is that acrylics and oils are different in the way solvents react with them. So mineral spirits, which is what can take off this varnish, isn’t really corrosive to either acrylics or oils. At least it it’s one of the least damaging to acrylics of the solvents that they use out there. And they don’t use it in conservation for like cleaning and stuff because it really isn’t very good at cleaning, but it doesn’t necessarily affect the oil too much. Other solvents, though, like xylene and other things, they will actually de-gloss or desaturate the color in acrylics. And other things like water even can affect acrylics where it’s not going to affect the oil paints as long as the oil paint hasn’t cracked or something like that. It forms a hard shell. So if in the future we go and we think I want to do some touch-ups or some changes and we take that varnish off, or if we’re just using some, there are certain mediums and things like when we do glazes and things like that, that – I don’t know, for the most part it’s not gonna affect me either because I don’t use mediums and when I do glazes, I’m just using oil, walnut oil. So it’s not a big deal. That’s not going to affect the acrylics. But it’s good to keep in mind that acrylics are affected by certain solvents that don’t affect oil paints.

[00:17:32] So it does limit us there, especially when for me my underpaintings, I leave them, many times spots of that oil painting coming through. A lot of people like to put down like a unifying color, maybe a burnt sienna or something like that as a wash over their whole canvas because they know that little bits of that are going to come through over the whole painting. Little tiny spots. They create kind of a harmonizing tone or color throughout all the other colors in the painting. But even without that, when I’m painting, I like to do a lot of dry brush glazing. And so I have parts of that underpainting that I want to come through in the end. Or I might leave areas that are more ‘washy’ and then other areas that are more refined and finished looking. There are so many different techniques we can do with oil painting. It really depends on what we’re trying to achieve. But we don’t want it, it’s not advisable, to use two different media like that that have that can be affected by different solvents in different ways.

[00:18:40] And of course, the dry time. So there is an alternative to it, though, that works out great. So I just want to do the caveat here. Acrylics and oils, they’re both great paint media to use. They’re just different. But there are a lot of pros to both of them and cons to both of them as well. I happen to love oil paint, so for me, I’m trying to find those things that are going to work well for oil painting.

[00:19:15] And acrylics overall, where an acrylic ground is used, I think even though Gamblin doesn’t like the idea of it because he doesn’t think it’s been tested enough, I feel strongly that it has been – for myself – not for anybody else, but for myself. I feel strongly that it has been. And I love working on this ABS plastic because it’s going to last. I mean, the plastic itself isn’t going to deteriorate with any appreciable deterioration for hundreds of years. Better than anything else out there – wood, canvas, anything else. There’s nothing that’s going to compete with it. Even aluminum isn’t going to compete with that. It’s fairly inexpensive, a lot less expensive than aluminum like Dibond or something like that. A lot easier to work with. I can paint directly on this. I don’t have to gesso it. It’s just so easy. So painting on top of acrylics in that way I think is fantastic. And as far as testing has gone, it shows that it’s good to do.

[00:20:16] So if we’re out on location and – so for me, I paint wet into wet – the initial washes, I’m not too concerned about it. But for those artists and there are a lot of them who are like this, for a lot of artists, they want to have in their initial washes some way to work with it in a way that it’ll dry so that they don’t disturb it and they can work over it and have that as kind of like their blueprint to follow. And they also do that so that the colors don’t get blended together. Things like that.

[00:20:57] And another reason for something like not doing the oils is to be able to rework a composition. So if we’re out on location and we’re trying to decide on the layout, let’s say we have a field with some trees and a river and mountains or whatever, and we we have some trees that work really well in our composition, but some trees that don’t seem to be quite in the spots that we want them, we move things around, that sort of thing. Well, let’s say we go through, we put down the composition, the design that we want, and we’re thinking “ahh I don’t know, I don’t think this is quite it”. Well, with acrylics, the idea of it is that you could then just it dries quick, you could paint over it, change things around easily. With oil paint, you have to wipe it off and start over again. But it can be problematic sometimes, especially as we start to get white added into our paint. It’s just a little bit more cumbersome to try to wipe something off and start over again. It’s very possible. I do it all the time, but it’s more cumbersome.

[00:22:05] But something that is a fantastic idea is to use watercolor. So watercolor, it’s a – so I have a caveat here with watercolor you don’t necessarily want, oK, no never mind, forget all that. With watercolor, just make sure that you don’t use opaque watercolor like a guache or something like that. We’re talking about a transparent watercolor in some type of a glaze. And you can paint it directly onto an acrylic ground without any problems.

[00:22:46] Now, the thing about watercolor is it’s always water-soluble. No matter how long it sits around, how dry it gets, you can take water and reconstitute it. It’s gonna become – you can move that color around or remove it or whatever. But if you put mineral spirits over it or oils over it or varnish over it, they’re not going to affect it at all. So if we use watercolor for those initial washes, then instead of acrylics, they dry instantly. I mean, basically, they dry instantly. We don’t have to wait for them to dry. And as long as we don’t use an opaque pigment, like get the watercolor too thick – the reason you wouldn’t want to get it too thick is what we talked about before that the increased pigment, the water is going to evaporate just like that out of that watercolor, then you’re left with this pigment. That pigment is a lot more absorbent and it’s going to soak up some of those oils from our paints and make our paints a little less stable. And besides that, it can become powdery and that can cause some problems just like any kind of dirt, you know, if we have, you know what I mean? Right? We don’t want to have anything too absorbent when we’re working with oil paints. So the absorbency of something like this isn’t sufficient enough to pull enough oil out of it. It’s just grabbing enough oil into that porosity of the acrylic to help it bind to it. But it’s not sucking out so much that, like wood, wood will continue to leach down in there. With the acrylic, it only does it so far and then it stops. So it’s not leaching all that acrylic or all that oil binder out of our oils till it becomes just a powder on there. We don’t have to worry about that.

[00:24:36] With watercolors, it’s the same thing as long as we don’t get it too thick. So then that dries and voila, if we don’t like our composition, we take a little water and wipe it off of there. Easy peasy. So instead of using, and the reason I brought all this up is because – I didn’t know a lot of this stuff – when I was going online – people have talked to me about doing acrylic underpaintings for a long time and I know some professional artists that do that. And I thought, “I don’t know it sounds like a good idea, I just don’t have any acrylics”. So right now I’m not too concerned about it because the way I paint it wasn’t a big thing for me. But I thought, you know, there might be some opportunities with it, some possibilities. So maybe I’ll try it out someday. Now, I know there’s a much better way – using watercolors instead of acrylics.

[00:25:27] So my recommendation is to use acrylics with acrylics, use oils with oils. And if you want to do an under glazing or the initial washes with something besides oils, then use watercolor. It works out great. It’s easy. And you can varnish over it. Now, in the future, if somebody removes that varnish and they get any water on there and you have any of that watercolor still showing through it, then there might be some problems because most solvents that they use to clean paintings with the first things they start wit, well, the first thing they start with is just a dry brush, but after that, they’re water-based solvents like water and something like that. So that can actually cause problems with the watercolor.

[00:26:22] So you’d want to seal that watercolor with like oil over it or something. At least in the long run, put something over it besides the varnish, because once they remove that varnish, if, you know, most of us don’t have to worry about this sort of thing, but even for your sake, for our sakes as artists, we might forget. I know I paint with things and 20, 30 years down the line, I don’t know what I used way back when necessarily on a particular painting. So if we’re ever worried about it, just remember that that watercolor is always going to come back with, be reconstituted by water or any solvents that have water in them. So just watch that. Pay attention to that.

[00:27:06] But otherwise, it’s a great substitute for acrylic under paintings and easy to use, easy to work with.

[00:27:15] And you can use the same brushes. OK. So, yeah, I used a lot of my oil painting brushes to do watercolors when I was in art school and they worked out great. I loved using bristle brushes for my watercolors, so don’t be afraid of that either. You don’t have to get all these fancy watercolor brushes to do it with. Use anything. It all works. It’s just that, remember if you have oil in the brush, then that might cause you some problems. But if your brushes are cleaned out well and there’s no oil in there, it’s good to go.

[00:27:47] So anyway, have fun. And for all those who have contemplated doing an acrylic underpainting, by now, you know that you have an alternative. And if you do an acrylic underpainting, you know that you should probably wait two to three days before you go and paint oils on top of it.

[00:28:03] And if you’ve thought about doing acrylic painting on top of oils, I wouldn’t recommend it. There is no mechanical bond there. It’s just it might be sticking to it and it might do that for a few years, but it’s not really bonded. It’s just sticking there, kind of like something that sticks to glass for a while and then suddenly it peels off like those vinyl stickers or something. It’s not really bonded to it. And you can always get it off of there eventually. Same thing with acrylic over oil. There’s no bonding. So have fun with that. I hope that helps. And happy painting.

Interested in checking out our free art lessons? You’re just one email address away from gaining access.